Mobile companion app + paired-device backend

New iOS-first companion (Expo SDK 54 + NativeWind v4) with three tabs:
Captures (the hero — floating gold mic, live mic-meter waveform,
expand-row playback), Generate (profile picker + speak + autoplay +
recent), and Voices (searchable profile list).

Pairing (V0): backend mints a one-time token, mobile scans/pastes the
voicebox:// URL, server returns a long-lived bearer it stores only as a
SHA-256 hash. Bearer-or-loopback auth applied to every user-data router
so binding 0.0.0.0 doesn't leak existing endpoints. Loopback callers
(the desktop app) keep their friction-free access.

Desktop Settings → Mobile pane: live host picker (LAN / Tailscale auto-
detected via the App-bundle binary path on macOS), QR rendering,
5-minute expiry countdown, copyable URL fallback, paired-device list
with revoke. Auto-closes when a new device pairs.

just dev now binds the backend to 0.0.0.0 so paired phones can reach
it — and just setup-python pins mlx-audio==0.4.1 + mlx-lm so fresh
Apple Silicon worktrees get a working STT path on first install.

backend/database/__init__.py

@@ -16,6 +16,8 @@ from .models import (
     GenerationSettings,
     GenerationVersion,
     MCPClientBinding,
+    PairedDevice,
+    PairingToken,
     ProfileChannelMapping,
     ProfileSample,
     Project,
@@ -37,6 +39,8 @@ __all__ = [
     "GenerationSettings",
     "GenerationVersion",
     "MCPClientBinding",
+    "PairedDevice",
+    "PairingToken",
     "ProfileChannelMapping",
     "ProfileSample",
     "Project",